Vena cava filters are utilized in conjunction with anti-coagulants and thrombolytic agents to prevent pulmonary embolism and other vascular diseases from occurring within the body. These devices are generally implanted within a vessel such as the inferior vena cava, and function by capturing blood clots (emboli) contained in the blood stream before they can reach the lungs and cause permanent damage to the patient.
To trap emboli, many conventional vena cava filters employ several independent filter legs that can be expanded in the vessel to form a conical-shaped filtering surface on which emboli can be collected. To enable ligation of the filter within the body, a hook, barb or other piercing means on the each filter leg can be used to anchor the filter along the cava wall. After a period of time within the body, tissue on the vessel wall begins to form about the ends of the filter legs, making removal of the device more difficult. In some circumstances, it may be desirable to remove the filter from the patient's body.